Filter systems with dirty air chamber spacer elements and methods of using the same

ABSTRACT

Filter systems and methods described herein include one or more spacer elements positioned in the dirty air chamber along with the filter elements attached to the spacer elements. The dirty air inlet delivers a dirty air stream into the dirty air chamber along a dirty air flow axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationSer. No. 61/648,494, filed on May 17, 2012, and U.S. ProvisionalApplication Ser. No. 61/790,184, filed on Mar. 15, 2013, both of whichare incorporated herein by reference in their entirety.

Filter systems having spacer elements positioned in the dirty airchamber between the tubesheet and filter elements and methods of usingthe filter systems are described herein.

BACKGROUND

Many industries encounter particulate matter suspended in theatmosphere. In some industries, this particulate matter is a valuableproduct (for example, starch), and it would be beneficial if thesuspended particulate matter could be recovered and reintroduced intothe process. For other industries (for example, metal or wood working),it may be desirable to remove the particulate matter from the air inorder to provide a clear working environment.

Systems for cleaning an air or other gas stream laden with particulatematter include filter systems that have filter elements disposed in ahousing. The filter element may be a bag, sock or cartridge including asuitable filter media, e.g., fabric, pleated paper, etc. The gas streamcontaminated with particulate matter is typically passed through thehousing so that the particulate matter is captured and retained by oneor more filter elements.

In a standard design, a filter system has a clean air chamber and adirty air chamber. The two chambers are separated by a structure that iscommonly referred to as a tubesheet. The tubesheet has a number ofopenings so that air can pass between the clean and dirty air chambers.The filter elements are positioned over the openings so thatparticulate-laden air (dirty air) introduced into the dirty air chambermust pass through a filter element to move into the clean air chamber.The particulate matter in the dirty air collects on the filter elementsas the air moves through the filter elements. From the clean airchamber, the cleaned air is exhausted into the environment, orrecirculated for other uses. See, for example, U.S. Pat. No. 3,942,962(Duyckinck), U.S. Pat. No. 4,218,227 (Frey), U.S. Pat. No. 4,424,070(Robinson), U.S. Pat. No. 4,436,536 (Robinson), U.S. Pat. No. 4,443,237(Ulvestad), U.S. Pat. No. 4,445,915 (Robinson), U.S. Pat. No. 4,661,131(Howeth), U.S. Pat. No. 5,207,812 (Tronto et al.), U.S. Pat. No.4,954,255 (Muller et al.), U.S. Pat. No. 5,222,488 (Forsgren), U.S. Pat.No. 5,211,846 (Kott et al.), U.S. Pat. No. 5,730,766 (Clements), U.S.Pat. No. 6,090,173 (Johnson et al.), U.S. Pat. No. 6,902,592 (Green etal.), and U.S. Pat. No. 7,641,708 (Kosmider et al.).

As the filter elements capture particulate matter, flow through thesystem is inhibited and periodic cleaning of the filter elements can beperformed to increase air flow through the system. Cleaning can beaccomplished by periodically pulsing a jet of pressurized air (oranother gas or gasses) into the interior of the filter element toreverse the air flow through the filter element, causing the collectedparticulate matter to be driven off of the filter element. Thepressurized air may be directed into venturi elements as described in,e.g. U.S. Pat. No. 3,942,962 (Duyckinck), U.S. Pat. No. 4,218,227(Frey), U.S. Pat. No. 6,090,173 (Johnson et al.), U.S. Pat. No.6,902,592 (Green et al.), and U.S. Pat. No. 7,641,708 (Kosmider et al.).

SUMMARY

The filter systems described herein include a plurality of spacerelements positioned in the dirty air chamber along with the filterelements attached to the spacer elements. In one or more embodiments,the spacer elements may be in the form venturi elements that have aconstricted throat between an inlet and an outlet.

In contrast to the arrangement of the spacer elements in the filterassemblies described herein, venturi elements in conventional filtersystems have typically been located in the clean air chamber and/orwithin the filter elements themselves. Operating such filter systems atan increased dirty air flow volume results in increased air speedswithin the dirty air chamber, which can potentially reduce the filterlife because of the abrasiveness of the particulate matter in the airwithin the dirty air chamber. For example, increased airflow through thefilter system causes increases in air/particulate velocity which canpotentially abrade holes in the filter elements.

By placing the spacer elements in the dirty air chamber, the volume ofthe dirty air chamber can, in some embodiments, be increased relative toconventional dirty air chambers in which the venturi elements areprovided in the clean air chamber and/or within at least a portion ofthe filter elements. The increased volume of the dirty air chamber canreduce the air velocities in the region of the dirty air chamberoccupied by the filter elements. The reduced air velocity in the dirtyair chamber can, in some embodiments, reduce abrasion of the media onthe filter elements.

In one or more embodiments of the filter systems described herein, thedirty air inlets may be configured to deliver dirty air streams directlyonto, past, and/or between the spacer elements in the dirty air chamberwhich can potentially provide additional advantages. In some instances,some of the particulate matter in the dirty air stream will be depositeddirectly in the collection hopper without ever reaching the filterelements. That can effectively reduce particulate loading on the filterelements and improve the life of the filter elements. Further, in someapplications, it may be valuable to avoid direct, high velocity contactbetween the particulate matter entrained in the dirty air stream and thefilter media of the filter elements.

Still another potential advantage of one or more embodiments of thefilter systems described herein is that the combination of the reducedair velocity in the larger dirty air chamber and, potentially, the earlyremoval of particulate matter (caused by directing the dirty air streamonto or past the exposed spacer elements in the dirty air chamber in oneor more embodiments) can reduce the amount of particulate matter thatremains suspended in the dirty air chamber, thus lowering particulateloading on the filter elements and extending filter life.

In a first aspect, one or more embodiments of the filter systemsdescribed herein include: a housing comprising a tubesheet separatingthe housing into a dirty air chamber and a clean air chamber; aplurality of spacer elements attached to the tubesheet, wherein eachspacer element of the plurality of spacer elements comprises a clean airinlet and a clean air outlet, and wherein the clean air inlet of eachspacer element of the plurality of spacer elements is located in thedirty air chamber; a plurality of apertures in the tubesheet, whereineach spacer element of the plurality of spacer elements is positionedover an aperture of the plurality of apertures in the tubesheet suchthat air passing from the dirty air chamber into the clean air chamberthrough each spacer element of the plurality of spacer elements passesthrough the aperture; a plurality of filter elements, wherein eachfilter element of the plurality of filter elements is attached to theclean air inlet of one spacer element of the plurality of spacerelements; and a dirty air inlet attached to the housing, wherein thedirty air inlet is configured to deliver a dirty air stream into thedirty air chamber.

In one or more embodiments of the filter systems described herein, thehousing comprises an end wall panel located across the dirty air chamberfrom the tubesheet, and wherein each spacer element of the plurality ofspacer elements and the filter element attached to each spacer elementextend across the dirty air chamber from the tubesheet to the end wallpanel.

In one or more embodiments of the filter systems described herein, thedirty air inlet is configured to deliver the dirty air stream into thedirty air chamber along a dirty air flow axis, and wherein the dirty airflow axis extends through or passes at least one spacer element of theplurality of spacer elements at a location between the clean air inletand the clean air outlet of the at least one spacer element such thatdirty air entering the dirty air chamber along the dirty air flow axiscontacts or passes at least one spacer element of the plurality ofspacer elements at a location between the clean air inlet and the cleanair outlet of the at least one spacer element before contacting theplurality of filter elements.

In one or more embodiments of the filter systems described herein, thedirty air inlet is configured to deliver the dirty air stream into thedirty air chamber along a dirty air flow axis, and wherein the dirty airflow axis does not extend through any filter elements of the pluralityof filter elements. In one or more embodiments, the dirty air flow axisextends through or passes at least one spacer element of the pluralityof spacer elements at a location between the clean air inlet and theclean air outlet of the at least one spacer element such that dirty airentering the dirty air chamber along the dirty air flow axis contacts orpasses at least one spacer element of the plurality of spacer elementsat a location between the clean air inlet and the clean air outlet ofthe at least one spacer element before contacting the plurality offilter elements.

In one or more embodiments of the filter systems described herein, eachspacer element of the plurality of spacer elements comprises an elementlength measured along an element axis extending though the clean airinlet and the clean air outlet of the spacer element, and wherein thedirty air inlet defines a width measured parallel to the element axisthat is less than or equal to 2 times an average element length of theplurality of element lengths of the plurality of spacer elements.

In one or more embodiments of the filter systems described herein, eachspacer element of the plurality of spacer elements comprises an elementlength measured along an element axis extending though the clean airinlet and the clean air outlet of the spacer element, and wherein thedirty air inlet defines a width measured parallel to the element axisthat is less than or equal to an average element length of the pluralityof element lengths of the plurality of spacer elements.

In one or more embodiments of the filter systems described herein, thedirty air inlet is configured to deliver the dirty air stream into thedirty air chamber along a dirty air flow axis, and wherein the dirty airinlet comprises a perimeter where the dirty air inlet enters the dirtyair chamber, and further wherein a projection of the perimeter parallelto the dirty air flow axis through the dirty air chamber does notintersect any filter elements of the plurality of filter elements.

In one or more embodiments of the filter systems described herein, thehousing comprises an end wall panel located across the dirty air chamberfrom the tubesheet, and wherein each spacer element of the plurality ofspacer elements and the filter element attached to each spacer elementextend across the dirty air chamber from the tubesheet to the end wallpanel, and further wherein the dirty air inlet extends across the dirtyair chamber from the tubesheet to the end wall panel.

In one or more embodiments of the filter systems described herein, thetubesheet comprises a dirty air side facing the dirty air chamber and aclean air side facing the clean air chamber, and wherein the clean airoutlet of each spacer element of the plurality of spacer elements ispositioned on the dirty air side of the tubesheet.

In one or more embodiments of the filter systems described herein, eachspacer element of the plurality of spacer elements does not extend intothe into the clean air chamber.

In one or more embodiments of the filter systems described herein, theplurality of spacer elements comprises a plurality of venturi elements,wherein each venturi element of the plurality of venturi elementscomprises a throat located between a clean air inlet and a clean airoutlet, and wherein the clean air inlet of each venturi element of theplurality of venturi elements is located in the dirty air chamber. Inone or more embodiments, the throat of each venturi element of theplurality of venturi elements is positioned on the dirty air side of thetubesheet and is exposed within the dirty air chamber.

In one or more embodiments of the filter systems described herein, thesystem further comprises a pulse-jet cleaning system comprising ablowpipe oriented to direct a pulse of air into the clean air outlet andtoward the clean air inlet of each spacer element of the plurality ofspacer elements.

In a second aspect, one or more embodiments of filter systems asdescribed herein may include: a housing comprising a tubesheetseparating the housing into a dirty air chamber and a clean air chamber;a plurality of spacer elements attached to the tubesheet, wherein eachspacer element of the plurality of spacer elements comprises a clean airinlet and a clean air outlet, and wherein the clean air inlet of eachspacer element of the plurality of spacer elements is located in thedirty air chamber; a plurality of apertures in the tubesheet, whereineach spacer element of the plurality of spacer elements is positionedover an aperture of the plurality of apertures in the tubesheet suchthat air passing from the dirty air chamber into the clean air chamberthrough each spacer element of the plurality of spacer elements passesthrough the aperture; a plurality of filter elements, wherein eachfilter element of the plurality of filter elements is attached to theclean air inlet of one spacer element of the plurality of spacerelements; and a dirty air inlet attached to the housing, wherein thedirty air inlet is configured to deliver a dirty air stream into thedirty air chamber along a dirty air flow axis, and wherein the dirty airflow axis extends through or passes at least one spacer element of theplurality of spacer elements at a location between the clean air inletand the clean air outlet of the at least one spacer element such thatdirty air entering the dirty air chamber along the dirty air flow axiscontacts or passes at least one spacer element of the plurality ofspacer elements at a location between the clean air inlet and the cleanair outlet of the at least one spacer element before contacting theplurality of filter elements.

In one or more embodiments of the filter systems described herein, thehousing comprises an end wall panel located across the dirty air chamberfrom the tubesheet, and wherein each spacer element of the plurality ofspacer elements and the filter element attached to each spacer elementextend across the dirty air chamber from the tubesheet to the end wallpanel.

In one or more embodiments of the filter systems described herein, thedirty air flow axis does not extend through any filter elements of theplurality of filter elements.

In one or more embodiments of the filter systems described herein, eachspacer element of the plurality of spacer elements comprises an elementlength measured along an element axis extending though the clean airinlet and the clean air outlet of the spacer element, and wherein thedirty air inlet defines a width measured parallel to the element axisthat is less than or equal to 2 times an average element length of theplurality of element lengths of the plurality of spacer elements.

In one or more embodiments of the filter systems described herein, eachspacer element of the plurality of spacer elements comprises an elementlength measured along an element axis extending though the clean airinlet and the clean air outlet of the spacer element, and wherein thedirty air inlet defines a width measured parallel to the element axisthat is less than or equal to an average element length of the pluralityof element lengths of the plurality of spacer elements.

In one or more embodiments of the filter systems described herein, thedirty air inlet comprises a perimeter where the dirty air inlet entersthe dirty air chamber, and further wherein a projection of the perimeterparallel to the dirty air flow axis through the dirty air chamber doesnot intersect any filter elements of the plurality of filter elements.

In one or more embodiments of the filter systems described herein, thetubesheet comprises a dirty air side facing the dirty air chamber and aclean air side facing the clean air chamber, and wherein the clean airoutlet of each spacer element of the plurality of spacer elements ispositioned on the dirty air side of the tubesheet.

In one or more embodiments of the filter systems described herein, eachspacer element of the plurality of spacer elements does not extend intothe into the clean air chamber.

In one or more embodiments of the filter systems described herein, theplurality of spacer elements comprises a plurality of venturi elements,wherein each venturi element of the plurality of venturi elementscomprises a throat located between a clean air inlet and a clean airoutlet, and wherein the clean air inlet of each venturi element of theplurality of venturi elements is located in the dirty air chamber. Inone or more embodiments, the throat of each venturi element of theplurality of venturi elements is positioned on the dirty air side of thetubesheet and is exposed within the dirty air chamber.

In one or more embodiments of the filter systems described herein, thesystem further comprises a pulse-jet cleaning system comprising ablowpipe oriented to direct a pulse of air into the clean air outlet andtoward the clean air inlet of each spacer element of the plurality ofspacer elements.

In a third aspect, one or more embodiments of methods of removingparticulate matter from dirty air may include: delivering dirty air intoa dirty air chamber of a housing comprising a tubesheet separating thehousing into the dirty air chamber and a clean air chamber, wherein thedirty air is delivered into the dirty air chamber in a dirty air streamalong a dirty air flow axis; and positioning a plurality of spacerelements and attached filter elements in the dirty air chamber, whereineach spacer element of the plurality of spacer comprises a clean airinlet and a clean air outlet, and wherein the clean air inlet of eachspacer element of the plurality of spacer elements is located in thedirty air chamber, and further wherein each spacer element of theplurality of spacer elements and the filter element attached to eachspacer element extend across the dirty air chamber from a tubesheet toan end wall panel located across the dirty air chamber from thetubesheet.

In one or more embodiments of the methods described herein, dirty airtraveling into the dirty air chamber through the dirty air inlet alongthe dirty air flow axis contacts at least one spacer element of theplurality of spacer elements or passes one or more spacer elements ofthe plurality of spacer elements at a location between the clean airinlet and the clean air outlet of each of the spacer elements beforecontacting the plurality of filter elements.

In one or more embodiments of the methods described herein, the dirtyair flow axis does not extend through any filter elements of theplurality of filter elements.

In one or more embodiments of the methods described herein, each spacerelement of the plurality of spacer elements comprises an element lengthmeasured along an element axis extending though the clean air inlet andthe clean air outlet of the spacer element, and wherein the dirty airinlet defines a width measured parallel to the element axis that is lessthan or equal to an average element length of the plurality of elementlengths of the plurality of spacer elements.

In one or more embodiments of the methods described herein, the dirtyair inlet comprises a perimeter where the dirty air inlet enters thedirty air chamber, and wherein a projection of the perimeter parallel tothe dirty air flow axis through the dirty air chamber does not intersectany filter elements of the plurality of filter elements.

In a fourth aspect, one or more embodiments of methods of removingparticulate matter from a dirty air stream may involve using any of thefilter systems described herein to remove that particulate matter.

The above summary is not intended to describe each embodiment or everyimplementation of the filter systems and methods described herein.Rather, a more complete understanding of the invention will becomeapparent and appreciated by reference to the following Description ofIllustrative Embodiments and claims in view of the accompanying figuresof the drawing.

BRIEF DESCRIPTIONS OF THE VIEWS OF THE DRAWING

FIG. 1 is a perspective view of one illustrative embodiment of a filtersystem as described herein.

FIG. 2 is a side view of the filter system depicted in FIG. 1.

FIG. 3 is a top view of the filter system depicted in FIGS. 1 and 2.

FIG. 4A is a cross-sectional view of the filter system of FIGS. 1-3taken along line 4A-4A in FIG. 3.

FIG. 4B is a schematic diagram depicting illustrative relationshipsbetween a dirty air flow axis and spacer elements.

FIG. 4C is a schematic diagram illustrating one illustrative angularrelationship between a dirty air flow axis and a spacer element axis asdescribed herein.

FIG. 4D is a cross-sectional view of an alternative illustrativeembodiment of a filter system including venturi elements as describedherein.

FIG. 4E is a cross-sectional view of another alternative illustrativeembodiment of a filter system including spacer elements as describedherein.

FIG. 5 is a cross-sectional view of the filter system of FIGS. 1-3 takenalong line 5-5 in FIG. 3;

FIG. 6 is partially exploded perspective view of the filter system ofFIGS. 1-5.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following description of illustrative embodiments, reference ismade to the accompanying figures of the drawing which form a parthereof, and in which are shown, by way of illustration, specificembodiments. It is to be understood that other embodiments may beutilized and structural changes may be made without departing from thescope of the present invention.

Referring to FIGS. 1-4A, one illustrative embodiment of a filter systemis depicted generally at 10. The filter system depicted in FIG. 1 has ahousing that may, in one or more embodiments, be generally in the shapeof a box that includes an upper wall panel 16, and two pairs of oppositeside wall panels 17 (one of which is depicted in FIG. 1), and end wallpanel 19.

The filter system 10 includes a dirty air inlet 11 for receiving dirtyor contaminated air (i.e., air with particulate matter entrainedtherein) into the filter system 10. A clean air outlet 13 (see, e.g.,FIGS. 3 and 4) may be provided for venting clean or filtered air fromthe filter system 10. The filter system 10 includes access openings 12in end wall panel 19 for filter elements (not shown in FIG. 1)configured together in a side-by-side arrangement. In use, each of theaccess openings 12 in end wall panel 19 is sealed by a cover (not shown)such that dirty air entering the filter system 10 does not escapethrough the access openings 12.

The depicted filter system 10 also includes blowpipes 20 (see, e.g.,FIGS. 2 and 3) as part of an optional pulse-jet cleaning system, withthe blowpipes 20 configured to direct a pulse of air into the filterelements as described herein. The filter system 10 may also include ahopper 18 to collect particulate matter separated from the dirty airstream as described herein. The hopper 18 may include sloped walls tofacilitate collection of the particulate matter and may, in someembodiments, include a driven auger or other mechanism for removing thecollected particulate matter.

It should be understood that features of the illustrative embodiments ofthe filter systems described herein that are not explicitly recited inthe claims are optional, e.g., features such as the number of filterelements, access openings, shape and/or size of the housing, etc. may bechanged in one or more alternative embodiments of filter systems asdescribed herein. It should also be understood that, other than thefilter media in the filter elements, the components of the filtersystems described herein will typically be constructed of materials(e.g., metals, polymers, ceramics, etc.) that are impermeable to air.

The illustrative embodiment of filter system 10 of FIG. 1 is depicted ina side elevation in FIG. 2, a top plan view in FIG. 3, and across-sectional view in FIG. 4A that is taken along line 4A-4A in FIG. 3to depict the interior of the filter system 10.

The interior of the filter system housing includes a tubesheet 22 thatseparates the interior volume of the housing into a clean air chamber 24and a dirty air chamber 26. As depicted in FIGS. 3 and 4A, the filtersystem 10 includes a clean air outlet 13 through which clean air exitsfrom the clean air volume during operation of the filter system 10. Theclean air outlet 13 may be positioned to remove clean air from anylocation in the clean air chamber 24. A dirty air inlet 11 is providedand dirty air enters the dirty air chamber 26 of the housing through thedirty air inlet 11.

The depicted filter system 10 includes spacer elements 30 and filterelements 40 in the dirty air volume 26. Each of the spacer elements 30includes a clean air inlet 32 and a clean air outlet 32, and is attachedto the tubesheet 22 over an aperture (see, e.g., apertures 28 in FIG.5). Clean air passing through the spacer element 30 from a filterelement 40 attached to the clean air inlet 32 of the spacer elemententers the clean air chamber 24 through the aperture in the tubesheet22.

In one or more embodiments of the filter systems described herein, thetubesheet 22 may be described as having a dirty air side facing thedirty air chamber 26 and a clean air side facing the clean air chamber24. Further, the clean air outlet 34 of each of the spacer elements 30may be described as being positioned, in one or more embodiments, on thedirty air side of the tubesheet 22. In one or more embodiments of thefilter systems described herein, the spacer elements 30 do not extendinto the clean air chamber 24.

In one or more embodiments of the filter systems described herein, thecombined length of each spacer element 30 and its attached filterelement 40 may extend from the tubesheet 22 to the end wall panel 19,across the entire width of the dirty air chamber 26.

In one or more embodiments of the filter systems described herein asdepicted in, e.g., FIG. 4A, the clean air inlets 32 of the spacerelements 30 are located in the dirty air chamber 26 and the filtered airoutlets 42 of the filter elements 40 are attached to the spacer elements30 such that air leaving the interior or filtered air volume of thefilter elements 40 through filtered air outlets 42 passes through theclean air inlets 32 of the spacer elements 30. In one or moreembodiments, the clean air inlets 32 of one or more of the spacerelements 30 may be located within the interior or filtered air volumesof the filter elements 40 such that, e.g., the filtered air outlet 42 ofthe filter element 40 is located closer to the tubesheet 22 than theclean air inlet 32 of the spacer element 30 to which it is attached.Even in such a case, however, the flow of dirty air along the dirty airflow axis 21 (described below) into the dirty air chamber 26 stillcontacts or passes the spacer elements 30 before contacting the filterelements 40. In one or more embodiments, the entire spacer element 30,from its clean air inlet 32 to its clean air outlet 34 may be located inthe dirty air chamber 26 with its exterior surface exposed to dirty airmoving through the dirty air chamber 26.

The dirty air inlet 11 is, in one or more embodiments of the filtersystems described herein, configured to deliver a dirty air stream intothe dirty air chamber 26 along a dirty air flow axis 21 that is, in oneor more embodiments, positioned in the central portion of the dirty airflow entering the dirty air chamber 26 through the dirty air inlet 11(such that, e.g., the dirty air flow axis could be described as the“central flow axis”). The dirty air flow axis 21 depicted in FIG. 4Amay, in one or more embodiments, be coincident with a line extendingthrough the geometric center of the opening through which dirty airenters the dirty air chamber 26 through the dirty air inlet 11. Thatline and the dirty air flow axis 21 defined by it may be described asaligned with the direction of flow into the dirty air chamber 26 whenthe filter system 10 is operating at or near its rated volumetriccapacity. Where, for example, the dirty air inlet 11 has a circularcross-section, the dirty air flow axis 21 will extend through the centerof that circle and be aligned with the direction of flow as describedherein.

In one or more embodiments of the filter systems described herein, thedirty air flow axis 21 may be described as extending through or passingat least one spacer element 30 at a location between the clean air inlet32 and the clean air outlet 34 of the spacer element 30. As a result,dirty air entering the dirty air chamber 26 along the dirty air flowaxis 21 may, in one or more embodiments, contact or pass the spacerelements 30 at locations between their clean air inlets 32 and clean airoutlets 34 before contacting the filter elements 40 in the dirty airchamber.

A schematic depiction of the arrangement of the dirty air flow axis 21with respect to a group of the spacer elements 30 is depicted in FIG.4B. Each of the spacer elements 30 has a clean air inlet 32 and a cleanair outlet 34 and defines an element axis 31 that extends through theclean air inlet 32 and the clean air outlet 34. The dirty air flow axis21 may be described as being located on a plane P while the element axes31 of the spacer elements 30 intersect, but are not located in the planeP. In one or more embodiments in which the dirty air flow axis 21intersects an element axis 31, the dirty air flow axis 21 may beperpendicular to the element axis 31 or form another included angle α(alpha) that is less than 90 degrees (see FIG. 4C). Alternatively, wherethe dirty air flow axis 21 does not intersect an element axis 31, theplane P in which the dirty air flow axis 21 is located and whichintersects all of the element axes 31 may be perpendicular to theelement axis 31 or form another included angle α (alpha) that is lessthan 90 degrees (as seen in FIG. 4C where the edge of plane P iscoincident with axis 21).

The result of the spatial relationships between the dirty air flow axis21 and the spacer elements 30 and filter elements 40 in filter systemsas described herein is that dirty air entering the dirty air chamber 26along the dirty air flow axis 21 may, in one or more embodiments,contact or pass the spacer elements 30 at locations between their cleanair inlets 32 and clean air outlets 34 before contacting the filterelements 40 in the dirty air chamber.

In other words, the spacer elements 30 and the dirty air inlet 11 arearranged such that the dirty air stream entering the dirty air chamber26 along the dirty air flow axis 21 contacts or passes the exteriorsurfaces of the spacer elements 30. In some cases, particulate matterentrained in the dirty air flow may pass by the spacer elements 30 andgo directly to the hopper 18 below the dirty air chamber 26. In somecases, particulate matter entrained in the dirty air flow contacts theexterior surface of one or more of the spacer elements 30, where it maybe redirected within the dirty air chamber 26 so that it is eventuallydelivered to the hopper 18 or to the filter elements 40.

The arrangement of the dirty air inlet and the dirty air flow axisdefined by it, relative to the spacer elements and filter elements may,in one or more embodiments, be alternatively or additionallycharacterized as follows.

In one or more embodiments, the dirty air flow axis 21 may be describedas not extending through any of the filter elements 40 in the dirty airchamber 26.

In one or more embodiments, the spacer elements 30 may be described ashaving an element length measured along their element axes 31 extendingthough their clean air inlets and clean air outlets. The dirty air inlet11 may be described as defining a width W (see FIG. 4A) measuredparallel to the element axes 31 that is less than or equal to an averageelement length of the element lengths of the spacer elements 30.Although the spacer elements 30 may typically all have the same elementlength, that is not required for the filter systems described herein.

In one or more alternative embodiments, the width W may be less than orequal to 2 times an average element length of the spacer elements 30(while in one or more alternative embodiments, the size of the dirty airinlet may be substantially larger—as discussed below in connection withFIG. 4E). Even in such an arrangement, one or more embodiments of thefilter systems described herein may still have a dirty air inlet thatdefines a dirty air flow axis 21 that extends through or passes by thespacer elements 30 at a location between their clean air inlets andoutlets and/or that does not extend through any of the filter elements40 in the dirty air chamber 26.

In one or more embodiments of the filter systems described herein, thedirty air inlet 11 may be described as having a perimeter where thedirty air inlet 11 enters the dirty air chamber 26 (see, e.g., the topview of FIG. 3). A projection of that dirty air inlet 11 perimeterparallel to the dirty air flow axis 21 through the dirty air chamber 26towards the hopper 18 does not intersect any filter elements 40 in thedirty air chamber 26.

Although not specifically described herein, the spacer elements used inthe filter systems described herein may be attached to tubesheets andfilter elements by any suitable technique or combination of techniques.The illustrative embodiments of the spacer elements 30 may, in one ormore embodiments, include flanges at their clean air outlets 34 andclean air inlets 32 that may facilitate attachment between the spacerelements 30, tubesheet 22, and filter elements 40 in manners that limitleakage through those junctions.

Furthermore, although the illustrative filter elements 30 are depictedas having a constant size (e.g., width, height, diameter, etc.) betweenthe clean air inlet 32 and the clean air outlet 34, the spacer elementsused in one of more alternative embodiments of the filter systemsdescribed herein may change in size between their inlets and outlets.One example of spacer elements that may change in size between theirinlets and outlets are commonly referred to as venturi elements.

Referring to the illustrative embodiment of filter system 110 depictedin FIG. 4D, the more generic spacer elements 30 seen in FIG. 4A havebeen replaced by venturi elements 130 with most other features andcomponents of the filter system 110 remaining largely the same as infilter system 10. The venturi elements 130 include a clean air inlet 132and a clean air outlet 134 (similar to the clean air inlets 32 andoutlets 34 of the spacer elements 30). The venturi elements 130 also,however, also include a throat 136 that constricts flow through theventuri element 130 because the open area within the throat 136 issmaller than the open area of the clean air inlet 132 and/or the cleanair outlet 134.

Examples of venturi elements that may potentially be used as spacerelements in the filter systems described herein may be described in,e.g. U.S. Pat. No. 3,942,962 (Duyckinck), U.S. Pat. No. 4,218,227(Frey), U.S. Pat. No. 6,090,173 (Johnson et al.), U.S. Pat. No.6,902,592 (Green et al.), and U.S. Pat. No. 7,641,708 (Kosmider et al.).Other potentially suitable venturi elements that may be used as spacerelements may be described in U.S. Provisional Patent Application No.61/648,492, titled AIR FILTER SYSTEM HAVING VENTURI ELEMENTS WITHEXTENDED PULSE OUTLETS, filed on May 17, 2012.

Because the throats 136 of the venturi elements 130 are located at anintermediate position between the clean air inlets 132 and the clean airoutlets 134, filter systems as described herein that use venturielements 130 as spacer elements may, in one or more embodiments, ashaving the throats 136 of the venturi elements 130 located in the dirtyair chamber 26 where they may further be described as having an exteriorsurface that is exposed within the dirty air chamber 26.

Another difference in the illustrative embodiment of filter system 110depicted in FIG. 4D from that depicted in FIG. 4A is the size of thedirty air inlet 111. In the illustrative embodiment depicted in FIG. 4D,the width (W′) of the dirty air inlet 111 may be taken in a directionparallel to the element axes extending though their clean air inlets 132and clean air outlets 134 of the venturi elements 130. The width W′ ofthe dirty air inlet 111 may be described as being less than the averageelement length of the element lengths of the venturi elements 130. Insuch an arrangement, the dirty air flow axis 21 defined by the dirty airinlet 111 extends through or passes by the venturi elements 130 at alocation between the dirty air side of the tubesheet 22 and the cleanair inlets 132 and/or that does not extend through any of the filterelements 40 in the dirty air chamber 26.

Still another alternative embodiment of a filter system as describedherein is depicted in connection with FIG. 4E. The primary differencebetween the illustrative embodiment of the filter system 210 depicted inFIG. 4E and those described elsewhere herein is in the size of the dirtyair inlet 211 (the other features and components of the filter system210 remaining largely the same as in the other illustrative embodimentsof filter systems described herein).

In the illustrative embodiment depicted in FIG. 4E, the width (W″) ofthe dirty air inlet 211 is measured in a direction parallel to theelement axes 31 extending though the clean air inlets 32 and clean airoutlets 34 of the spacer elements 30 (which could, in one or moreembodiments, be venturi elements as described herein). The width W″ ofthe dirty air inlet 211 may be described as being as large as the widthof the dirty air chamber 26 from the tubesheet 22 to the end wall panel19. Although not depicted in FIG. 4E, the depth of the dirty air inlet211 may be equal to or less than the depth of the dirty air chamber 26as measured between the opposing side wall panels 17—i.e., the dirty airinlet 211 may, in one or more embodiments, occupy the entire portion ofthe upper wall panel 16 located above the dirty air chamber 26 (see,e.g., FIGS. 1-3).

Another manner in which the arrangement of spacer elements 30, filterelements 40, and the dirty air inlet 211 may be characterized is that,in one or more embodiments of the filter systems described herein, thedirty air inlet 211 may have a width W″ that is equal to or less thanthe width of the dirty air chamber 26 as measured from the dirty airside of the tubesheet 22 to the end wall panel 19 and, further, that thespacer elements 30 and their attached filter elements 40 also extendfrom the dirty air side of the tubesheet 22 to the end wall panel 19.

The larger dirty air inlet 211 depicted in connection with filter system210 may, in one or more embodiments, contribute to reduced velocitywithin the dirty air chamber 26 which may, as described herein provideadvantages in one or more filter systems as described herein.

Referring to FIGS. 5 and 6, which are, respectively, a cross-sectionalview of the filter system of FIG. 1 taken along line 5-5 in FIG. 3 and apartially exploded perspective view of the filter system 10 with some ofthe walls removed to reveal the spacer elements 30 (in the form ofventuri elements as discussed herein) and filter elements 40 located inthe dirty air chamber of the filter system 10. It should be understoodthat the specific features and components depicted connection with thefilter system 10 seen in FIGS. 5 and 6 are illustrative in nature onlyand, unless explicitly recited in the claims, they should not beconstrued to limit the scope of the present invention.

The apertures 28 in the tubesheet 22 over which the spacer elements 30are positioned are seen in the cross-sectional view of FIG. 5. Althougheach spacer element 30 is depicted as being positioned over only oneaperture 28, in one or more alternative embodiments, the clean airoutlet 34 of each spacer element 30 may be positioned over more than oneaperture in the tubesheet 22 (although it may be desirable to match thesize and/or shape of the aperture 28 to the size and/or shape of theclean air outlet 34).

Also seen in FIG. 5 are optional yokes 44 that may, in one or moreembodiments, be attached to the spacer elements 30 and/or the tubesheet22. The yokes 44 may be provided to assist in supporting the filterelements 40 within the housing of the filter system 10. The use of yokesand/or other structures for supporting filter elements in a filtersystem may be described in, e.g., U.S. Pat. No. 3,942,962 (Duyckinck),U.S. Pat. No. 4,218,227 (Frey), U.S. Pat. No. 5,562,746 (Raether), U.S.Pat. No. 6,090,173 (Johnson et al.), U.S. Pat. No. 6,902,592 (Green etal.), and U.S. Pat. No. 7,641,708 (Kosmider et al.).

Although the filter elements 40 depicted in FIGS. 4-6 are in the form oftwo-part cartridges, the filter systems described herein can be adaptedto use a variety of filter elements provided the filter elements can beused in conjunction with spacer elements as described herein. In one ormore embodiments, for example, the filter elements may take the form of,e.g., bags, socks, cartridges, etc.

The blowpipes 20 depicted in connection with the illustrative embodimentof filter system 10 are configured to direct air into the spacerelements 30 through the apertures 28 in the tubesheet 22. The air fromeach of the blowpipes 20 enters the clean air outlet 34 of acorresponding spacer element 30 and exits into the filter element 40through the clean air inlet 32 to remove particulate matter from thefilter elements 40 in a manner similar to that described in, e.g., U.S.Pat. No. 4,218,227 (Frey), U.S. Pat. No. 5,562,746 (Raether), U.S. Pat.No. 6,090,173 (Johnson et al.), U.S. Pat. No. 6,902,592 (Green et al.),U.S. Pat. No. 7,641,708 (Kosmider et al.), and U.S. Pat. No. 8,075,648(Raether).

The blowpipes 20 may be provided as part of a pulse-jet cleaning systemincluding one or more sources of pressurized gas (e.g., air), valves anda control system. Illustrative embodiments of potentially suitablepulse-jet cleaning systems may be found in, e.g., U.S. Pat. No.4,218,227 (Frey), U.S. Pat. No. 5,562,746 (Raether), U.S. Pat. No.6,090,173 (Johnson et al.), U.S. Pat. No. 6,902,592 (Green et al.), U.S.Pat. No. 7,641,708 (Kosmider et al.), and U.S. Pat. No. 8,075,648(Raether). In one or more embodiments of the filter systems describedherein, the blowpipes used may include the diverging nozzles and othercomponents and methods described in U.S. Provisional Patent ApplicationNo. 61/772,198 titled DIVERGING NOZZLES AND FILTER ELEMENT CLEANINGSYSTEMS USING DIVERGING NOZZLES, filed on Mar. 4, 2013.

U.S. Provisional Patent Application No. 61/789,385, titled OVATE TUBULARFILTER CARTRIDGES AND FILTER SYSTEMS USING THE SAME, filed on Mar. 15,2013, describes filter cartridges that may, in one or more embodiments,be used in the filter systems described herein.

In addition, U.S. Provisional Patent Application No. 61/648,494, titledFILTER ASSEMBLY WITH DIRTY AIR CHAMBER VENTURI ELEMENTS, filed on May17, 2012 may describe features and arrangements of filter systems andsystems that may be used in connection with the filter systems describedherein.

The complete disclosure of the patents, patent documents, andpublications identified herein are incorporated by reference in theirentirety as if each were individually incorporated. To the extent thereis a conflict or discrepancy between this document and the disclosure inany such incorporated document, this document will control.

Illustrative embodiments of filter systems and methods are discussedherein some possible variations have been described. These and othervariations and modifications in the invention will be apparent to thoseskilled in the art without departing from the scope of the invention,and it should be understood that this invention is not limited to theillustrative embodiments set forth herein. Accordingly, the invention isto be limited only by the claims provided below and equivalents thereof.It should also be understood that this invention also may be suitablypracticed in the absence of any element not specifically disclosed asnecessary herein.

1. A filter system comprising: a housing comprising a tubesheetseparating the housing into a dirty air chamber and a clean air chamber;a plurality of spacer elements attached to the tubesheet, wherein eachspacer element of the plurality of spacer elements comprises a clean airinlet and a clean air outlet, and wherein the clean air inlet of eachspacer element of the plurality of spacer elements is located in thedirty air chamber; a plurality of apertures in the tubesheet, whereineach spacer element of the plurality of spacer elements is positionedover an aperture of the plurality of apertures in the tubesheet suchthat air passing from the dirty air chamber into the clean air chamberthrough each spacer element of the plurality of spacer elements passesthrough the aperture, a plurality of filter elements, wherein eachfilter element of the plurality of filter elements is attached to theclean air inlet of one spacer element of the plurality of spacerelements; and a dirty air inlet attached to the housing, wherein thedirty air inlet is configured to deliver a dirty air stream into thedirty air chamber.
 2. A filter system according to claim 1, wherein thehousing comprises an end wall panel located across the dirty air chamberfrom the tubesheet, and wherein each spacer element of the plurality ofspacer elements and the filter element attached to each spacer elementextend across the dirty air chamber from the tubesheet to the end wallpanel.
 3. A filter system according to claim 1, wherein the dirty airinlet is configured to deliver the dirty air stream into the dirty airchamber along a dirty air flow axis, and wherein the dirty air flow axisextends through or passes at least one spacer element of the pluralityof spacer elements at a location between the clean air inlet and theclean air outlet of the at least one spacer element such that dirty airentering the dirty air chamber along the dirty air flow axis contacts orpasses at least one spacer element of the plurality of spacer elementsat a location between the clean air inlet and the clean air outlet ofthe at least one spacer element before contacting the plurality offilter elements.
 4. A system according to claim 1, wherein the dirty airinlet is configured to deliver the dirty air stream into the dirty airchamber along a dirty air flow axis, and wherein the dirty air flow axisdoes not extend through any filter elements of the plurality of filterelements.
 5. A filter system according to claim 4, wherein the dirty airflow axis extends through or passes at least one spacer element of theplurality of spacer elements at a location between the clean air inletand the clean air outlet of the at least one spacer element such thatdirty air entering the dirty air chamber along the dirty air flow axiscontacts or passes at least one spacer element of the plurality ofspacer elements at a location between the clean air inlet and the cleanair outlet of the at least one spacer element before contacting theplurality of filter elements.
 6. A filter system according to claim 1,wherein each spacer element of the plurality of spacer elementscomprises an element length measured along an element axis extendingthough the clean air inlet and the clean air outlet of the spacerelement, and wherein the dirty air inlet defines a width measuredparallel to the element axis that is less than or equal to 2 times anaverage element length of the plurality of element lengths of theplurality of spacer elements.
 7. A filter system according to claim 1,wherein each spacer element of the plurality of spacer elementscomprises an element length measured along an element axis extendingthough the clean air inlet and the clean air outlet of the spacerelement, and wherein the dirty air inlet defines a width measuredparallel to the element axis that is less than or equal to an averageelement length of the plurality of element lengths of the plurality ofspacer elements.
 8. A filter system according to claim 1, wherein thedirty air inlet is configured to deliver the dirty air stream into thedirty air chamber along a dirty air flow axis, and wherein the dirty airinlet comprises a perimeter where the dirty air inlet enters the dirtyair chamber, and further wherein a projection of the perimeter parallelto the dirty air flow axis through the dirty air chamber does notintersect any filter elements of the plurality of filter elements.
 9. Afilter system according to claim 1, wherein the housing comprises an endwall panel located across the dirty air chamber from the tubesheet, andwherein each spacer element of the plurality of spacer elements and thefilter element attached to each spacer element extend across the dirtyair chamber from the tubesheet to the end wall panel, and furtherwherein the dirty air inlet extends across the dirty air chamber fromthe tubesheet to the end wall panel.
 10. A filter system according toclaim 1, wherein the tubesheet comprises a dirty air side facing thedirty air chamber and a clean air side facing the clean air chamber, andwherein the clean air outlet of each spacer element of the plurality ofspacer elements is positioned on the dirty air side of the tubesheet.11. A filter system according to claim 1, wherein each spacer element ofthe plurality of spacer elements does not extend into the clean airchamber.
 12. A filter system according to claim 1, wherein the pluralityof spacer elements comprises a plurality of venturi elements, whereineach venturi element of the plurality of venturi elements comprises athroat located between a clean air inlet and a clean air outlet, andwherein the clean air inlet of each venturi element of the plurality ofventuri elements is located in the dirty air chamber.
 13. A filtersystem according to claim 12, wherein the throat of each venturi elementof the plurality of venturi elements is positioned on the dirty air sideof the tubesheet and is exposed within the dirty air chamber.
 14. Afilter system according to claim 1, wherein the system further comprisesa pulse jet cleaning system comprising a blowpipe oriented to direct apulse of air into the clean air outlet and toward the clean air inlet ofeach spacer element of the plurality of spacer elements.
 15. A filtersystem comprising: a housing comprising a tubesheet separating thehousing into a dirty air chamber and a clean air chamber; a plurality ofspacer elements attached to the tubesheet, wherein each spacer elementof the plurality of spacer elements comprises a clean air inlet and aclean air outlet, and wherein the clean air inlet of each spacer elementof the plurality of spacer elements is located in the dirty air chamber;a plurality of apertures in the tubesheet, wherein each spacer elementof the plurality of spacer elements is positioned over an aperture ofthe plurality of apertures in the tubesheet such that air passing fromthe dirty air chamber into the clean air chamber through each spacerelement of the plurality of spacer elements passes through the aperture,a plurality of filter elements, wherein each filter element of theplurality of filter elements is attached to the clean air inlet of onespacer element of the plurality of spacer elements; and a dirty airinlet attached to the housing, wherein the dirty air inlet is configuredto deliver a dirty air stream into the dirty air chamber along a dirtyair flow axis, and wherein the dirty air flow axis extends through orpasses at least one spacer element of the plurality of spacer elementsat a location between the clean air inlet and the clean air outlet ofthe at least one spacer element such that dirty air entering the dirtyair chamber along the dirty air flow axis contacts or passes at leastone spacer element of the plurality of spacer elements at a locationbetween the clean air inlet and the clean air outlet of the at least onespacer element before contacting the plurality of filter elements.
 16. Afilter system according to claim 15, wherein the housing comprises anend wall panel located across the dirty air chamber from the tubesheet,and wherein each spacer element of the plurality of spacer elements andthe filter element attached to each spacer element extend across thedirty air chamber from the tubesheet to the end wall panel.
 17. A filtersystem according to claim 15, wherein the dirty air flow axis does notextend through any filter elements of the plurality of filter elements.18. A filter system according to claim 15, wherein each spacer elementof the plurality of spacer elements comprises an element length measuredalong an element axis extending though the clean air inlet and the cleanair outlet of the spacer element, and wherein the dirty air inletdefines a width measured parallel to the element axis that is less thanor equal to 2 times an average element length of the plurality ofelement lengths of the plurality of spacer elements.
 19. A filter systemaccording to claim 15, wherein each spacer element of the plurality ofspacer elements comprises an element length measured along an elementaxis extending though the clean air inlet and the clean air outlet ofthe spacer element, and wherein the dirty air inlet defines a widthmeasured parallel to the element axis that is less than or equal to anaverage element length of the plurality of element lengths of theplurality of spacer elements.
 20. A filter system according to claim 15,wherein the dirty air inlet comprises a perimeter where the dirty airinlet enters the dirty air chamber, and further wherein a projection ofthe perimeter parallel to the dirty air flow axis through the dirty airchamber does not intersect any filter elements of the plurality offilter elements.
 21. A filter system according to claim 15, wherein thetubesheet comprises a dirty air side facing the dirty air chamber and aclean air side facing the clean air chamber, and wherein the clean airoutlet of each spacer element of the plurality of spacer elements ispositioned on the dirty air side of the tubesheet.
 22. A filter systemaccording to claim 15, wherein each spacer element of the plurality ofspacer elements does not extend into the clean air chamber.
 23. A filtersystem according to claim 15, wherein the plurality of spacer elementscomprises a plurality of venturi elements, wherein each venturi elementof the plurality of venturi elements comprises a throat located betweena clean air inlet and a clean air outlet, and wherein the clean airinlet of each venturi element of the plurality of venturi elements islocated in the dirty air chamber.
 24. A filter system according to claim23, wherein the throat of each venturi element of the plurality ofventuri elements is positioned on the dirty air side of the tubesheetand is exposed within the dirty air chamber.
 25. A filter systemaccording to claim 15, wherein the system further comprises a pulse jetcleaning system comprising a blowpipe oriented to direct a pulse of airinto the clean air outlet and toward the clean air inlet of each spacerelement of the plurality of spacer elements.
 26. A method of removingparticulate matter from dirty air, the method comprising: deliveringdirty air into a dirty air chamber of a housing comprising a tubesheetseparating the housing into the dirty air chamber and a clean airchamber, wherein the dirty air is delivered into the dirty air chamberin a dirty air stream along a dirty air flow axis; and positioning aplurality of spacer elements and attached filter elements in the dirtyair chamber, wherein each spacer element of the plurality of spacercomprises a clean air inlet and a clean air outlet, and wherein theclean air inlet of each spacer element of the plurality of spacerelements is located in the dirty air chamber, and further wherein eachspacer element of the plurality of spacer elements and the filterelement attached to each spacer element extend across the dirty airchamber from a tubesheet to an end wall panel located across the dirtyair chamber from the tubesheet.
 27. A method according to claim 26,wherein dirty air traveling into the dirty air chamber through the dirtyair inlet along the dirty air flow axis contacts at least one spacerelement of the plurality of spacer elements or passes one or more spacerelements of the plurality of spacer elements at a location between theclean air inlet and the clean air outlet of each of the spacer elementsbefore contacting the plurality of filter elements.
 28. A methodaccording to claim 26, wherein the dirty air flow axis does not extendthrough any filter elements of the plurality of filter elements.
 29. Amethod according to claim 26, wherein each spacer element of theplurality of spacer elements comprises an element length measured alongan element axis extending though the clean air inlet and the clean airoutlet of the spacer element, and wherein the dirty air inlet defines awidth measured parallel to the element axis that is less than or equalto an average element length of the plurality of element lengths of theplurality of spacer elements.
 30. A method according to claim 26,wherein the dirty air inlet comprises a perimeter where the dirty airinlet enters the dirty air chamber, and wherein a projection of theperimeter parallel to the dirty air flow axis through the dirty airchamber does not intersect any filter elements of the plurality offilter elements.